Application of diamond coatings onto small dental tools

Abstract

Small dental tools such as burs and drills are commonly used in dental practice and laboratory. Conventional diamond burs used for grinding operations have a number of problems associated with heterogeneity of the crystallites, decreased cutting efficiency, need for repeated sterilisation and short life. These burs are manufactured by imbedding diamond particles into the burs using a suitable binder matrix material. The use of a diamond coating may offer an improvement in dental bur technology. Chemical vapour deposition (CVD) of diamond coatings onto the cemented tungsten carbide WC–Co substrate is problematic. Generally the adhesion of diamond coating to cemented carbide substrate is poor. It is obvious that the binder materials such as cobalt can suppress diamond growth and enhance graphitic deposits, which cause poor adhesion and low diamond nucleation density. The effects of key process parameters such as filament position, filament and substrate temperature and pre-treated substrate material on the coating properties have been investigated using a variety of analytical techniques. Characterisations of the substrates and polycrystalline diamond film morphology were analysed by scanning electron microscopy (SEM). The chemical composition was evaluated by energy dispersive spectroscopy (EDS). Raman spectroscopy was used to assess the carbon-phase purity and give an indication of the stress levels in the as-grown polycrystalline diamond films.